1. Field of the Invention
The present invention relates to vibration wave (type) driving apparatus having an output shaft.
2. Related Background Art
Conventionally, several types of vibration motors are known as vibration wave driving apparatus having an output shaft. For example, as shown in FIG. 11, there is a known motor as disclosed in Japanese Patent Application Laid-Open No. 5-38170.
This motor has a vibration member 140 constructed in such structure that piezoelectric elements 142 and 144 are placed between metal blocks 150 and 152 as elastic members of hollow cylinder shape and that the two metal blocks are coupled by a coupling bolt 154 of cylindrical shape placed on the inner periphery side of these metal blocks 150, 152.
On the other hand, a motor housing (outer case) has a case body 170 and a lid 171 arranged at an opening end of the case body and provided with a motor support 171a of cylindrical shape located in a motor center region. This motor support 171a constitutes a motor supporting portion and a bearing 172 is placed on the motor support 171a and journals an output shaft 134. Further, a collar 175 of ring shape provided on a cylinder bore portion of the coupling bolt 152 is fixed to the motor support 171a to support the vibration member 140.
A rotating body (rotor portion) 130 as a contact body is placed on one side of the vibration member 140. This rotor portion 130 keeps a rotor body 132 of disc shape in press contact with an end face of the metal block 152 by spring force of spring 133. The spring 133 is placed between rotor body 132 and support plate 136 and the rotor body 132 is coupled to the output shaft 134.
In the above prior art example, however, since the bearing 172 is positioned by inserting it from one end of the motor support 171a of the lid 171 making the case, it is necessary to fix the bearing to the case by bonding or the like, in order to avoid slipping-off of the vibration member.
Accordingly, the vibration wave driving apparatus seems susceptible to further improvement in structure toward simpler fixing of the bearing for the output shaft and higher reliability without use of bonding.
One aspect of this invention is a vibration wave driving apparatus in which a bearing member journaling an output shaft is provided so as to be located between an inner periphery portion of an elastic member with a shaft center portion thereof being formed in hollow shape along an axial direction and a fastening member fastening this elastic member to an electro-mechanical energy conversion element, wherein the shaft center of the elastic member is determined by the output shaft journaled on the bearing member and wherein the bearing member is interposed between the elastic member and the fastening member, whereby the bearing member can be fixed more easily and surely without use of an adhesive or the like.
Another aspect of this invention is a vibration wave driving apparatus in which a bearing member journaling an output shaft is provided on an inner periphery portion of an elastic member with a shaft center portion being formed in hollow shape along an axial direction and near a distal end of a fastening member fastening the elastic member to an electro-mechanical energy conversion element, wherein the shaft center of the elastic member is determined by the output shaft journaled on the bearing member, whereby the fixing of the bearing member becomes much easier and higher in reliability.